package com.java.collection;

import java.util.*;

public class Client {
	//psvm
	public static void main(String[] args) {
		List<?> list = new ArrayList<String>();
		list.add(null);

		Set<String> set = new HashSet<String>();
		set.add(null);
		Iterator it = set.iterator();

		System.out.print(set.size());

		Map map = new HashMap();
		map.put(null,null);
		System.out.print(map.size());
	}
}
